React interview questions in Hindi #12 When rendering a list what is a key and what is it's purpose?
0Keys help React identify which items have changed, are added, or are removed. Keys should be given to the elements inside the array to give the elements a stable identity. The best way to pick a key is to use a string that uniquely identifies a list item among its siblings. Most often you would use IDs from your data as keys. When you don't have stable IDs for rendered items, you may use the item index as a key as a last resort. It is not recommend to use indexes for keys if the items can reorder, as that would be slow
The purpose of the "key" prop is to help React's reconciliation algorithm perform updates in an optimized manner. When a list of elements is rendered, React needs to keep track of the relationship between the old list and the new list when the list items change, are added, or removed. The "key" prop provides React with a way to uniquely identify elements and determine how to update the DOM efficiently.
By providing a "key" prop, you enable React to:
Optimize Updates: React can efficiently determine whether an element in the list has changed or if it has been moved, added, or removed. This helps minimize unnecessary DOM updates and enhances performance.
Preserve State: If you don't provide a "key" prop, React might have a harder time tracking the state of individual elements, which could lead to incorrect updates or unnecessary re-rendering.
Maintain Stable Order: The "key" prop ensures that the order of elements remains stable. Without keys, React may re-order elements in ways you might not expect.Please do like share and comment if you like the video please do hit like and if you have any query please write it comment box
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